1. Field of the Invention
This invention relates to a medical device employing a needle having a guard member which permanently locks in place to protect against accidental needle sticks after the needle has been used. More particularly, it relates to an improved locking element to hold the guard securely in the locked position.
2. Background Discussion
In U.S. patent application Ser. No. 06/849,148, filed Apr. 7, 1986, entitled MEDICAL DEVICE, and U.S. patent application Ser. No. 07/035,434, filed Apr. 7, 1987, and entitled MEDICAL DEVICE, both of these applications assigned to ICU Medical, Inc., the assignee of this application, there is described medical devices using needles having movable guard members which are locked permanently in position after the needle is used. Both of these applications are incorporated herein by reference. In both of these applications, the locking member is mounted on the needle shaft and it is bonded to the shaft by an adhesive. The locking device includes a recessed portion which serves to capture a wedge-type collar piece integral with one end of the guard member. With the collar piece wedged in the recessed portion, the guard is locked in a permanent position once it has been moved forward to cover the tip of the needle.
The purpose of the guard member is to prevent accidental needle sticks. If, however. the bond between the locking element and the exterior surface of the needle fails, the guard member would move and possibly expose the tip of the needle. Moreover, in mass producing such medical devices, it is both expensive and inconvenient to secure the locking element to the needle by means of an adhesive. Although the medical devices described in the above-identified applications represent a substantial improvement in disposable needles, it is desirable to improve their design so that there would not be an accidental failure of the bond between the locking element and the shaft of the needle and would also enable the devices to be mass produced rapidly and inexpensively.